id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
4863	TH crashes if you reify the Name of a dfun	guest	simonpj	"{{{
Prelude Language.Haskell.TH Language.Haskell.TH.Syntax> $(fmap show (classInstances ''Eq [ConT ''Int] >>= reify . head) >>= lift)

<interactive>:1:3:
    Exception when trying to run compile-time code:
      <interactive>: panic! (the 'impossible' happened)
  (GHC version 7.0.1 for x86_64-unknown-linux):
	reifyType PredTy
    <pred>base:GHC.Classes.Eq{tc 23} ghc-prim:GHC.Types.Int{(w) tc 3J}

Please report this as a GHC bug:  http://www.haskell.org/ghc/reportabug

      Code: (>>=)
              fmap
                (show)
                ((>>=)
                   classInstances 'Eq [Language.Haskell.TH.Syntax.ConT 'Int]
                   (.) reify head)
              lift
    In the expression:
      $(fmap show (classInstances 'Eq [ConT 'Int] >>= reify . head)
      >>=
        lift)
    In an equation for `it':
        it
          = $(fmap show (classInstances 'Eq [ConT 'Int] >>= reify . head)
            >>=
              lift)
}}}
The same thing happens when compiling with ghc rather than using GHCi.  Also, it looks like the pretty printer is displaying {{{ ''Eq }}} and {{{ ''Int }}} incorrectly."	bug	new	low	_|_	Template Haskell	7.0.1				Linux	x86_64 (amd64)	Compile-time crash